Approved United States Coast Guard personal flotation devices are required for many water activities. Personal flotation devices come in many shapes, colors and materials, but typically incorporate buoyant foam material. A popular type of personal flotation device is designed as a vest that fits around the user's neck and upper torso, commonly secured to the user via a zipper, adjustable straps or belts.
Swimwear-style personal flotation devices have been developed, particularly for use with children. These devices incorporate buoyant foam material into a garment designed for continuous wear, similar to a swimming suit. As with most personal flotation devices, maintaining the location of the buoyant foam material with respect to the user's head and torso is critical to ensure proper flotation. Incorporating buoyant foam material into swimwear-style personal flotation devices has presented unique challenges. Should the buoyant foam material shift from its prescribed location in the chest and upper back areas, or curl or fan excessively, the attitude of the user in the water can be adversely influenced and the personal flotation device not perform the functions for which it is intended.
Solid foam blocks have been used in swimwear-style personal flotation devices in an effort to achieve proper flotation. The solid foam blocks, for example made from PVC foam, have been sewn into various portions of the swimsuit in an effort to maintain buoyancy and balance when worn by a user in the water. Using solid PVC blocks reduce the likelihood that the buoyant foam material will curl or fan. However, solid foam blocks are bulky, add significant weight and cost to the product and are cosmetically unappealing.
Flexible buoyant foam material, for example multiple layers of the polyethylene foam more commonly found in traditional life jackets and vests, is a more promising alternative. Use of multiple flexible layers of buoyant material avoids much of the bulk and weight associated with solid foam blocks. The stretchy nature of the fabrics used as a shell and lining for swimwear-style personal flotation devices presents new challenges when multiple layers of buoyant material are used. While such layers maintain an ideal position in flotation garments made from limited stretch material such as woven fabrics or marine netting, when used in the stretchy swimwear-style fabrics (for example neoprene or knit fabrics), the layers tend to shift from the prescribed location or curl or fan excessively. This results in an undesirable change in the attitude of the user in the water and threatens the proper performance of the personal flotation device.
Prior attempts to solve problems associated with using multiple layers of polyethylene foam with swimwear-style personal flotation devices have been largely unsuccessful. Bonding the polyethylene foam layers together to form a single layer reduces the curling and fanning issues while avoiding the weight issues present when using solid blocks of foam. But this solution requires the addition of an adhesive application step, which in turn introduces significant complexities in the manufacture of the personal flotation device. It also raises questions about the durability of the bond over time and use. Finally, use of an adhesive introduces safety concerns about the proper ventilation for the adhesive, both during manufacture and subsequent storage by the seller and end user, as well as long term potential health effects on the user.
Sewing pieces of the swimwear-style fabric directly to the flexible foam material to serve as attachment points to secure the foam into the garment is likewise not feasible. Such stitching is not an option when using preferred polyethylene foam material in the thickness required in swimwear-style personal flotation devices.
Thus, there is a need for improved stabilization of multiple layers of flexible foam material when used in personal flotation devices to reduce curling and fanning issues and avoid bulk and weight while providing a cosmetically appealing flotation device.